In the prior art, disclosures of pipetting systems appear in various U.S. Patents:
U.S. Pat. No. 3,572,552 to P. W. Guinn, 3-30-71, disclosed an externally calibrated form of dispenser employing deflectable diaphragm communicating with a plurality of tips; gas or liquid was employed;
U.S. Pat. No. 3,807,235 to I. Lefkovits and O. Kamber, 4-30-74, disclosed vacuum actuation of a diaphragm to draw it into hemispherical chambers defining volume drawn into respective cannulas;
U.S. Pat. No. 3,982,438 to W. J. Byrd, 9-28-76, disclosed a system analogous to the Lefkowitz and Kamber system with positive and negative pressure actution of the diaphragm and hemispherical recesses below as well as above the diagram;
U.S. Pat. No. 4,047,438 to T. Sekine, 9-13-77, disclosed a system in which local hemispherical convolutions of the flexible diaphragm were permanent and were forcibly flattened to actuate the system;
U.S. Pat. No. 4,158,035 to T. Haase and W. Byrd, 6-12-79, disclosed a further system with hemispherical recesses both above and below the flexible diaphragm.